From this point there is difficulty for the student to trace the course of the walls. Part can be identified at the beginning of the Seraglio enclosure; but part cannot be seen at all except from the sea. Approach is forbidden by the harsh "Yasak, Yasak" of the sentries. The walls from the Acropolis, now Seraglio point, to the marble tower at the end of the Land walls, had 188 towers, and were above five miles in length. Unlike those on the Golden Horn they were built close to the sea, and the line of their course "was extremely irregular, turning in and out with every bend of the shore, to present always as short and sharp a front as possible to the waves that dashed against them." At least thirteen gates are known. The first is the Cannon gate, Top Kapoussi, "a short distance to the south of the apex of the promontory," called by the Greeks the gate of S. Barbara, from the church which stood near it. Close to it was the Mangana, or arsenal of the city. The next gate is Deirmen Kapoussi (gate of the mill), of which the Greek name is unknown. It was near here that the great ice-floes broke over the wall; and a number of inscriptions westwards from this point mark the restorations of Theophilus. Near it "a hollow now occupied by market gardens indicates the site of the Kynegion, the amphitheatre erected by Severus when he restored Byzantium," where in later times Justinian II. set his feet on Leontius and Apsimarus (see above, p. 55). The next gate is the Demir Kapoussi, with a small opening through which it is said that the Sultanas sewn in sacks were thrown, and near it large chambers possibly used as prisons. A little further on there are arched buttresses through which water used to be brought from the holy spring of the ancient Church of S. Saviour, and on which was built the famous Indjili Kiosk, from which the Sultans would view the splendid panorama of hill and sea which stretches before it. Here, too, was the palace of Mangana, and not far off the atrium of Justinian mentioned by Procopius, where stood the splendid statue of Theodora. Further south was the Church of the Theotokos Hodegetria, where originally the icon of the B. V. M. attributed to S. Luke (see p. 263) was kept. The place of the small gate named after the church is shown by two slabs, built into the inner side of the gateway now walled up, bearing the inscription "Open me the gates of righteousness that I may go in and praise the Lord." It was through this gate that John VI. Palæologus entered in 1355, having tricked the guards by pretending that his ships were wrecked. Beyond Ahour Kapoussi is the ruined wall of the palace of Hormisdas, where once was the Bucoleon, and then comes the small bay which formed the imperial port of the Bucoleon. A little further one sees clearly the Church of SS. Sergius and Bacchus above the ruined wall, and here was the gate on which was an inscription which commemorated the famous Nika insurrection. Beyond